Bullet traps for high-volume applications, such as a commercial shooting range, commonly use a snail-trap design. Snail traps typically comprise two funnel plates positioned relative to one another to form an inlet to a trap pipe. The funnel plates are commonly angled relative to one another to define a mouth opposite from the inlet which is significantly wider than the inlet. The angled orientation is designed to deflect or funnel bullets towards the inlet when a shooter fires at the mouth of the trap. The trap pipe defines a circular bore, and the inlet leads to the circular bore. The inlet extends longitudinally along the pipe, and the inlet is aligned tangentially with the circular bore, usually at the top of the bore, forming the shape of a snail shell. The alignment of the inlet to the circular bore is configured to redirect the bullet's linear path to a circular path within the circular bore.
In other words, if the snail trap were viewed from the side with the mouth on the left, the trap pipe on the right, and the inlet tangentially aligned with the top of the circular bore, the bullet would enter the circular bore through the inlet travelling left-to-right, and the linear velocity would be converted into a circular path travelling clockwise within the circular bore along an inner surface of the circular bore. Eventually, the kinetic energy of the bullet is exhausted through friction between the bullet and the inner surface of the circular bore, and the bullet will eventually fall to a bottom of the circular bore under the effect of gravity. The trap pipe commonly includes a bottom slot extending longitudinally along the trap pipe, and the settled bullets fall through this bottom slot into a collection mechanism to keep the circular bore clear.
Once fired, a bullet possesses an extremely high amount of kinetic energy which must be dissipated for the bullet to come to rest within the circular bore. Depending upon the cartridge, bullets can also travel at extremely high velocities, sometimes exceeding 4000 feet-per-second. As described, this energy is dissipated through friction between the bullet and the inner surface of the circular bore which generates heat. Because of the high amounts of energy being dissipated and the extreme velocities of the bullets, the trap pipe and the funnel plates must be designed to withstand abrasion. The demands of the application often require that the funnel plates and the trap pipe be fabricated from specific abrasion resistant materials, such as Abrasion Resistant (“AR”) steel alloys, like AR400 or AR500, which are typically very expensive compared to common mild steel grades. These hardened materials are difficult to work with during fabrication. The transition between the funnel plates and the trap pipe must be smoothly contoured to prevent ricochet back towards the mouth of the trap which often requires the funnel plates to be welded directly to the trap pipe. This construction creates a very large, expensive, and heavy welded assembly which is difficult to transport, install, and replace at the end of its service life. Each snail trap also typically has a rating limit for the calibers which it is capable of handling, such as rimfire-only or handgun-only at the lower end up to big bore rifle caliber ratings, such as the 0.50 Browning Machine Gun (“BMG”) or larger. Once fabricated, the individual snail trap is typically not upgradeable to handle more powerful calibers than those for which it was originally designed.